Method of fractionating fatty pitches



United States Patent METHOD OF FRACTIONATING FATTY PITCHES Leo Garwin, Oklahoma City, Okla, assignor to Kerr- McGee Oil industries, Inc., a corporation of Delaware No Drawing. Filed May 7, 1958, Ser. No. 733,502

9 Claims. (Cl. 260-975) This invention relates to a'method of separatinga high softening point resinous material from fatty pitches as a fluid phase. method for solvent treating fatty type pitches to separate at least a resinous material having a softening point of at least 170 F. More specifically, this invention relates to a method for solvent extracting fatty type pitches with hydrocarbons containing from 5 to 8 Carbon atoms when saturated and from 4 to 7 carbon atoms when unsaturated.

The hydrocarbons of l to 8 carbon atoms are known to be useful solvents for treating animal and vegetable oils and/or fats. In fact, propane, pentane and hexane are used in a number of commercial installations to treat fats and oils to remove color bodies, to obtain vitamin concentrates and to produce edible and industrial oils having improved color, odor and related stability properties.

In addition to the above, the prior art further teaches that the results achieved with the individual hydrocarbons are essentially the same. In general, the lighter hydrocarbons, for instance propane, appear to be preferred for treating oils and fats perse and the heavier hydrocarbons, for example, pentane and hexane, are preferred for extracting the oils from meal cake, i.e. crushed seed pulp. This preference does not appear to be based on any difference in the fractionation effect of these solvents but on the ease with which they may be adapted to the particular product being treated or for other reasons.

Even though the solvent treatment of fats and oils is quite popular, a considerable volume of fats and oils is still subjected to distillation to produce improved edible and industrial products. The bottoms from the distillation process are generallyrefer'red to as fattypitches and specifically are referred to as the pitch of the specific oil or fat subjected to distillation, for example, tall oil pitch, soybean pitch, stearine pitch, etc. I

Thees pitches have properties which are dependent to a certain extent on the severity of the distillation to which the fat or oil is subjected, and consequently, may be either soft or hard, friable materials.

The pitches have a number of uses, and these uses result primarily from the low price of the pitches. For instance, one use of the pitches is in the manufacture of bituminous tile or floor coverings. Although 'a considerable volume of the fatty pitches is used for floor coverings, the fatty pitches impart certain properties to the finished product which limit its commercial acceptance. For example, the

soft pitchesgenerally contain suflicient carboxylic groups to reduce the alkali resistance of the floor covering and, in addition to this objectional feature, the soft pitches require the use of an inordinate amount of high softening point bituminous materials, for example, blown asphalt, gilsonite, asphaltic resins and asphaltenes, to give the floor covering suflicient indentation resitance and hardness. The use of large amounts of high softening point bituminous material lowers the pigmentation response of the binder, increasing the pigmentcost and the cost of the finished floor covering.

This invention further relates to -a Patented June 14, 1960 On the other hand, if hard and friable fatty pitches are used, such fatty pitches normally have been subjected to cracking conditions during their production, and their chemical structure has undergone a change as a result of polymerization. Some of the more valuable oils have been lost due to this molecular change upon cracking and polymerization.

When the hard fatty pitches are used in the manufacture of floor coverings, the amount of soft asphalt has to be increased and the resulting tile may have undesirable temperature susceptibility properties and low resistance to oxidation;

It is readily apparent to those skilled in this art that the formulator must compromise on the properties desired in the finished floor covering when using the fatty pitches in his formulation.

- Therefore, an object of this invention is to provide a method for solvent treating fatty pitches to produce a relatively high softening point resin which is free of some of the aforesaid undesired properties and to produce a light fraction containing no resinous materials.

It is a further object of this invention to provide a method of separating a high softening point resinous material from fatty pitches as a fluid phase.

Another object of this invention is to enable the processors of fats and oils to upgrade distillation bottoms and thus increase the market value and acceptance of pended claims.

In accordance with these objects, a fatty pitch is intimately contacted with a suitable hydrocarbon solvent, having the characteristics described hereinafter, at elevated temperature and pressure conditions which give the hydrocarbon a density of the prescribed magnitude. A further aspect of this invention comprises treating a fatty pitch with at least two volumes of a hydrocarbon solvent of the prescribed number of carbon atoms for each volume of pitch with the temperature and pressure conditions being adjusted to separate a heavy and a light fraction as fluid phases. An additional aspect of this invention relates to the discovery that the high molecular weight hydrocarbons, i.e., those having between about 5 to 8 carbon atoms, have a different fractionating effect on the fatty pitches than that exhibited by propane.

For example, propane separates from the soft fatty pitches a relatively soft heavy fraction, but pentane, on the other hand, separates from the same pitch a heavy fraction having a softening point of approximately ISO-200 F. and higher. Pentane and the higher molecular weight hydrocarbons, ie those containing up to about 8 carbon atoms, separate not only a high softening point resinous fraction but separate said fraction as a fluid phase, and this prevents the plugging of the fractionation system thereby allowing continuous operation of the fractionator.

To specifically illustrate this difference between the action of propane and pentane on fatty pitches, a tall oil pitch was treated separately with these solvents at room temperature. It was found that the heavy fraction obtained with propane had a softening point of about 120 F. but the pentane separated fraction had a softening point of I210 F. Also, it was observed that thepentane derived fraction separated as a solid precipitate which critical temperature. i i 7 It should be noted that tall oil pitch, although not ifrom tall oil pitch increased but {the softening'point tended V to be lower. "On the' other :hand,-.it"was' observed that iziat-a temperature of 200,F; pentane separ'ated froni Ztall oil pitchla heavyifraction'havinga softening point i. of at least.170"- F. and the yield wasessentiallythe same 7 that obtained at room temperature with pentanel 'This 1s contrary to the teachings of the hydrocarbon solvent qtreating art. :Norm'ally itis expected that the softening zpomt-cfthe. heavy fraction will. decreaseand its -''y'ield ":;increase.withincreasingteinperamrei-"t -.ci

QItiWQS also; discovered that "the :light .fractionx( having a softeningpoint of about 100 F.) from thehi'g'h*tem gperatureftjreatmentWithpehtanecouldbe further fraction-j r ated to give a secondary 'heavyafraction ihaving a: softening P t approximately the same 1as'that :ofithe heavy fraction obtained by propane treatment. 'ineans that. the fatty pitches such fas'tall o'il'pitch may. befractionated by means of the highermolecular-wei'ght solvent hydrocarbons into a-high softening 'poin'nfi'iable resin and a low softening point resin having good ductility propertiesg- The light oily fraction obtained. byfthis process has interesting possibilities as a constituent of paints and other protective coatings.

As indicated previously, the hydrocarbons suitable for :3 use in my invention may be either saturated or'unsaturated in nature. The saturated hydrocarbons have from. S'to.

1 8carbon' atoms, inclusive, and may-bestraight chain, branched chain or cyclic in nature. The unsaturated'hy- I drocarbons useful in my invention contain from 4 to 7 carbon atomsand likewise may be straight chain, branched l chain or cyclic in nature. The preferred unsaturated hydrocarbons are the mono-olefinsp It should-hemmed that the cyclic hydrocarbons are not aswell suited for this invention as the others because the cyclic hydrocarbon densities ata giventemperature and pressure-are gen-i V erally higher than thoseof their corresponding straight chain homologues, and the cyclic compounds. thus rea 7 quire a higher temperatureto obtain the desired fractionation, i i V In general, the temperature must beat :least about 200 F. and less than the paracritical temperature to separate the heavy resinous fraction as a fluid phase, The j paracritical temperature is generally considered to be from 50 F. below thecritical temperature to-above the I generally. classified as, being derived from either vegetable or animal fats or oils, has chemical and physicalproperties which would certainly properly includeit in a fattyg'pitch category along with'the pitches ,derivecl from soybeanoils, I v

I tallow,, coconut oils, etc; M

The volume ratio of solvent to pitch islcritical. If'the volume ratio of solvent to. pitch is not at leastZ to 1, no

phaseseparation occurs. In fact, theselectivity isvery poor at yolume ratios between about 2 to 1 and 4 to-1. Therefore, it is preferred that at least .4 volumes of solvent 7 be used for each volume of pitch, toincrease thes electivity and thus insure that optimum yieldscf the desired fractions will be obtained. Generally, 5 rt0.1,0.volu.rnes of solvent to each volume of pitch will be used in thepractice of this invention although at times the ratio may be even ashighasZQtolorhigher. Although the conditions necessary to separate the firactions in accordance with'the spirit ofthis invention are obtained by adjusting the temperature, pressure and V V solvent topitch ratio, a definite relationship between the temperature and pressure is necessary to accomplish the 7 result. Forexample, the pressure must be atleast equivalent to the equilibrium pressure of the solvent at the Separation temperature and suflicient to give thesolvent Iawfie v d ns y pertain r s b d fiaaacaqs ff in mally the heavy fraction having a softening point of at least 170 F. is obtained as a fluid phase at a solvent density of at least 0.45 g./ml.and less than 0.60 g./ml. The preferred solvent density for eflecting the separa- 5 tion of a heavy fraction having'a-softening point of at least 170" F. is between about 0.48 and 0.55 g./ml.

The density of the scluentat which a secondary heavy phase maybe separated is between about 0.25 g./ml. and'0.45 g ./ml. Generally, the secondary heavy fraction 10 will have a softening point between 1 00 and 135 F. fandalightcolonz Although the solvent is readily recovered from the separated fractions by flashing distillation, 'etc., a preferred method of recovering solvent comprises raising the '15 temperature of the solvent mixtureabove the critical temthe solvent a density less than about.0.25 g./ml. 'Under 7 these conditions the solvent and ,separatedfi'action demix the cooling water requirements are also" considerably lower. Pumping capacity and costs are reduced.

LMy invention is' finther illustrat'ed by the exam'ples. or I I Exar nple l A sample of crude tall oil -Aointol-C, a produet of Arizona Chemical Company, wasused in this experiment. 'This particular crude tall oil was characterized by the -following analysis: 7

40 One volume of this crudetalloil was intimately mixed with 10 volumes of pent-ane and let stand at ambient temperature, approximately 85 F; The light phase was decanted from the heavy phase. The .separate fractions ,wereheated to remove the pentane. fIfhe yield of light phase was'98.2% by-weightlandlhe yieldof'heary Phase was 1.8% by weight.v The color ratios of thelight fraction and the heavy fraction were 0.0015 to. Q.111 refspectivelyf 1. T" V Thercolor ratios, as used above, .we r'e obtained from readings on a Klett-Sumrfierson photoelectric colorimeter 501 using a green filter. The sampleswere diluted I. in aromafienaphtha (Bronocp Hi-Sol itZO) 'andthe reading' compared withthat for jgils'bnitej,

.When' propane was substituted for pentane in the treatlightfractions were of the same magnitude, i. e,, there is obtained a very low yield of heavy fraction andthe great .bulkpf the stock remain's dissolved in the.solyent. It should-be noted that comparable yield results are reported in the published literature for other animaland vegetable oils whenjtreated with these same solvents.

' Q Example-11* V i A tall oil pitch,a bottom product of the distillation of the r crude tall oil, showed the followingpr'operties:

7 Acid N0;68,.color.ratio Q,O, semi-solid tacky appearance. 1 I l 5 V Onevolunie of this tall oil pitch was plaeedin a boinb and'10 volumesfof propane was added. The bombTwas rocked :tofintimately contact its contents a'nd then allowed to stand. The ambient; emper;

9 F. andfthe pressurepf the bomb "W "l40 p .s.i,'g. Two phases formed on standing. Thesejwefe separated byrext-ruding the heavy phase through the va'lye on' the bot tom of the bomb. The heavy' phasewasjfluid' perature of the solvent and adjusting the pressure to give "and the solvenh free of any dissolved pitch' fractiong may 20 be removedoverhead from the pressurc'vessel. This 7 reiwas" about the vessel and extruded readily. The heavy fraction was heated to remove the last of the solvent. The heavy fraction was obtained in a yield of 71.6% by weight and had the following characteristics: Softening point 125 F., color ratio of 0.067. The light fraction, after solvent removal, was an oil having a color ratio of 0.012.

Example 111 The experiment of Example 11 was repeated using pentane instead of propane. The heavy fraction was present in the contacting vessel as a precipitate instead of as a fluid phase. The phases were separated by decantation of the light phase. The yield of heavy fraction was 18%. This fraction had a softening point of 181 F. and a color ratio of 0.101. The light fraction had a color ratio of 0.016.

Example IV The experiment of Example III was repeated except that the temperature of the bomb was raised to 200 F. The bomb pressure at this temperature was 60 p.s.i.g. The heavy phase was present within the bomb as a fluid phase and extruded very readily through the valve in the bottom of the bomb. The heavy fraction, obtained in 29.3% weight yield, had a softening point of 191 F.

The light phase was given a further treatment at a higher temperature to separate a light resinous fraction. The temperature was raised to 390 F. The bomb pressure at this temperature was 525 p.s.i.g. The secondary heavy phase was present within the bomb as a fluid phase and was extruded very readily from the vessel. The yield of light fraction was 40.9% by weight and the yield of the secondary heavy fraction (soft resins) was 29.5% by weight. The secondary heavy fraction had a softening point of 132 F. The light fraction was a reddish oil.

When hexane was substituted for pentane, the yield of primary heavy fraction tended to be less and the softening point tended to be higher.

What is claimed is:

1. A method of separating a high softening point resinous material from fatty pitches as a fluid phase comprising treating each volume of pitch with at least 2 volumes of a hydrocarbon solvent selected from the class consisting of saturated aliphatic hydrocarbons having 5 through 8 carbon atoms, inclusive, and mono-olefin hydrocarbons having 4 through 7 carbon atoms, inclusive, at elevated temperature and pressure, the temperature being at least 200 F. and less than the para-critical temperature of the solvent, the pressure being at least equivalent to the equilibrium pressure of the solvent at this temperature and being adjusted to provide a solvent density greater than 0.45 g./ml. and less than 0.60 g./ml. to produce a fluid heavy phase and a lighter phase and separating said heavy phase while fluid from the lighter phase to obtain a high softening point resin.

2. The method of claim 1 wherein the fatty pitch is tall oil pitch.

3. The method of claim 1 wherein the hydrocarbon solvent is pentane.

4. A method of separating a high softening point resinous material from fatty pitches as a fluid phase comprising treating each volume of fatty pitch with at least 4 volumes of a hydrocarbon solvent selected from the class consisting of saturated aliphatic hydrocarbons having 5 through 8 carbon atoms, inclusive, and mono-olefin hydrocarbons having 4 through 7 carbon atoms, inclusive, at elevated temperature and pressure, the temperature being at least 200 F. and less than the paracritical temperature of the solvent, the pressure being at least equivalent to the equilibrium pressure of the solvent at this temperature and being adjusted to provide a solvent density greater than 0.48 g./ml. and less than 0.55 g./ ml. to produce a fluid heavy phase and a lighter phase, and separating said heavy phase while fluid from the lighter phase to obtain a high softening point resin.

5. The method of claim 4 wherein the fatty pitch is tall oil pitch.

6. The method of claim 4 wherein the hydrocarbon solvent is pentane.

7. A method of separating fatty pitches into at least two fractions wherein all fractions separate as fluid phases and the heaviest fraction has a softening point of at least F. comprising treating each volume of fatty pitch with at least 2 volumes of a hydrocarbon solvent selected from the class consisting of saturated aliphatic hydrocarbons having 5 through 8 carbon atoms, inclusive, and mono-olefin hydrocarbons having 4 through 7 carbon atoms, inclusive, elevated temperature and pressure, the temperature being at least 200 F. and less than the paracritical temperature of the solvent, the pressure being adjusted to provide a solvent density greater than 0.45 g./ml. and less than 0.60 g./ml., separating the resulting fluid heavy phase while fluid from the resulting lighter phase to obtain a resinous fraction having a softening point of at least 170 F., adjusting the temperature and pressure on the lighter phase to provide a solvent density less than 0.45 glue]. and greater than 0.27 g/ml. to produce a secondary fluid heavy phase and a secondary lighter phase, and separating said secondary heavy phase while fluid from the secondary lighter phase to obtain a secondary resinous fraction and a secondary phase containing pitch oil.

8. The method of claim 7 wherein the fatty pitch is tall oil pitch.

9. The method of claim 7 wherein the hydrocarbon solvent is pentane.

References Cited in the file of this patent UNITED STATES PATENTS 2,652,412 Mattikow Sept. 15, 1953 2,802,849 Passino Aug. 13, 1957 2,866,739 Ciesielski et a1 Dec. 30, 1958 

1. A METHOD OF SEPARATING A HIGH SOFTENING POINT RESINOUS MATERIAL FROM FATTY PITCHES AS A FLUID PHASE COMPRISING TREATING EACH VOLUME OF PITCH WITH AT LEAST 2 VOLUMES OF A HYDROCARBON SOLVENT SELECTED FROM THE CLASS CONSISTING OF SATURATED ALIPHATIC HYDROCARBONS HAVING 5 THROUGH 8 CARBON ATOMS, INCLUSIVE, AND MONO-OLEFIN HYDROCARBONS HAVING 4 THROUGH 7 CARBON ATOMS, INCLUSIVE, AT ELEVATED TEMPERATURE AND PRESSURE, THE TEMPERATURE BEING AT LEAST 200*F. AND LESS THAN THE PARA-CRITICAL TEMPERATURE OF THE SOLVENT, THE PRESSURE BEING AT LEAST EQUIVALENT TO THE EQUILIBRIUM PRESSURE OF THE SOLVENT AT THIS TEMPERATURE AND BEING ADJUSTED TO PROVIDE A SOLVENT DENSITY GREATER THAN 0.45 G./ML. AND LESS THAN 0.60 G./ML. TO PRODUCE A FLUID HEAVY PHASE AND A LIGHTER PHASE AND SEPARATING SAID HEAVY PHASE WHILE FLUID FROM THE LIGHTER PHASE TO OBTAIN A HIGH SOFTENING POINT RESIN. 